This invention relates to adhesives and labels which are resistant to chemical degradation and are capable of resisting shrinkage and distortion when affixed to surfaces having relatively high temperatures.
Where long life and protection from abrasion and solvent or chemical attack have been desired, it has been customary to employ metal nameplates or labels covered with a protective layer, such as a plastic film or a heat-cured coating of epoxy resin. Labels of this kind are relatively expensive and sometimes difficult to apply. In addition, they often are inadequate in withstanding relatively high temperature exposure and attack by chemicals such as battery acids.
Thus, plastic film and heat-cured overcoatings typically are applied making use of relatively expensive ovens to produce heat which can adversely affect or distort underlying layers. Even where the labels can withstand indirect heating, if they are affixed to a surface which is subject to constant or intermittent heating, the result can be shrinkage, distortion and curling, as well as discoloration.
Accordingly, there is a need for economical pressure-sensitive adhesives and labels which are resistant to chemical degradation and at the same time able to withstand relatively high temperatures. The invention provides for such products by using specifically formulated adhesive-containing resins in a novel arrangement of coating layers.
It is a principal object of the invention to provide adhesives and labels which are resistant to chemical degradation as well as shrinkage and distortion at elevated temperatures. A related object is to provide resistance to battery acids, as well as resistance to shrinkage and distortion at the temperatures where batteries commonly operate. In the case of vehicles, this requires the ability to withstand temperatures close to the boiling point of water.
It is another object of the invention to provide adhesives and labels which have a reduced tendency to discolor or undergo mechanical degradation. A related object is to resist bodystock and laminate degradation of adhesives and labels which are subject to battery acid exposure.
Other objects of the invention will become apparent from the disclosure which follows.